The present invention relates to electronics assemblies, and is primarily concerned with racked assemblies. Many such assemblies will be located in racks for housing in for example nineteen inch cabinets, or other size cabinets such as twenty three inch or metric cabinets. The assemblies may for instance be employed as servers for a number of systems, for example in local area networks (LANs), wide area networks (WANs), telecommunications systems or other operations such as database management or as internet servers.
Such an assembly will typically comprise a supporting frame that houses a motherboard or backplane and a number of daughterboards or module cards that extend in planes generally perpendicular to the plane of the motherboard and which are connected to the motherboard by connectors, e.g. high density connectors, so that the daughterboards can simply be located on guides and pushed toward the motherboard in order to connect them to it.
In such assemblies, the motherboard may need to be removed for general maintenance purposes, upgrading or the like and so the frame of the assembly will normally provide for removal of the motherboard therefrom and re-insertion therein.
One problem that can be encountered during servicing and maintenance of the assembly during operation thereof is that certain components, especially certain power components located on the motherboard can be subjected to relatively high voltages for electronics systems, for example 48 V d.c. which, although not dangerous to health, can cause minor shocks.
According to one aspect, the present invention provides an electronics assembly which comprises:
(i) a frame;
(ii) a motherboard that is located within the frame; and
(iii) one or more daughterboards that extend in a plane generally perpendicular to the plane of the motherboard;
wherein the motherboard has a protective shield that extends over the major surface thereof that is oriented toward the or each daughterboard and which has an aperture therein to allow electrical connection between the motherboard and the or each daughterboard.
The assembly according to the invention may be one in which the motherboard is arranged in a substantially horizontal plane beneath a number of daughterboards located in parallel, vertical planes above the motherboard. This assembly is intended, as far as possible, to be in continuous operation, and may be designed so that one or more daughterboards can be removed and replaced, for example for repair or for maintenance purposes, while the system as a whole is still operating.
The fact that the motherboard is arranged in a horizontal plane in this embodiment, and can be located directly beneath locations where certain operations will be performed, such as ejection and removal of the daughterboards, and replacement thereof, can mean that small foreign bodies, for example, screws, clips, nuts and bolts, can be inadvertently dropped between the cords forming the daughterboards and onto the motherboard. This can lead to short circuits between various components and failure of the system. According to the present invention however, the motherboard is protected from the effect of any such objects by the protective shield. In addition, any danger of someone inadvertently touching live parts of the circuit is removed or reduced.
The protective shield may, in many instances, form part of a protective housing that extends over both major surfaces of the motherboard, and may also extend around each edge of the motherboard. Such a protective housing may thus enclose the motherboard substantially entirely other than any electrical connectors thereon. Where the protective shield forms part of a housing that extends around the motherboard, the invention has the advantage that it can be removed from the electronics assembly and can be subjected to dirty environments without risk to the performance thereof. Indeed, the protective shield and any housing that includes the shield may be formed from metal, for example the same metal forming the rest of the chassis of the assembly such as aluminium zinc plated steel, and therefore be relatively robust.
Where the protective shield is formed from a metal it will be necessary to isolate the motherboard from the shield, for example by providing one or more spacing elements that will physically separate the motherboard from the protective shield.
Such electronics assemblies are normally made so that the motherboard can itself be removed for repair or maintenance purposes, and the shield can be provided with location elements for locating the motherboard correctly with respect to the frame forming the chassis or a part of the chassis of the assembly. Typically such locating elements would comprise screws or bolts that screw into the frame if the motherboard is to be fixed in that way, or guidance and location elements such as pins and corresponding recesses may be employed where the motherboard housing is intended to be slid into place in the frame. It is also possible for the protective shield, especially when forming part of a housing, to be provided with guidance and location elements to enable it to be located correctly, with respect to guides for the daughterboards rather than with respect to the frame as a whole.
According to another aspect, the invention provides an electronics assembly which comprises:
(i) a frame;
(ii) a motherboard that is located within the frame; and
(iii) one or more daughterboards that extend in a plane generally perpendicular to the plane of the motherboard;
wherein the motherboard is arranged in a substantially horizontal plane beneath a protective shield that extends over the upper surface of the motherboard.
According to a further aspect, the invention provides a frame for an electronics assembly, which comprises:
(i) a motherboard that is located within the frame; and
(ii) a location for receiving at least one daughterboard so that it extends in a plane generally perpendicular to the motherboard;
wherein the motherboard has a protective shield that extends over the major surface thereof that is oriented toward the or each daughterboard and which has an aperture therein to allow electrical connection between the motherboard and the or each daughterboard.
Such a motherboard may be permanently secured within the frame or it may be removable therefrom as described above. Where the motherboard is removable from the frame, the shield may remain in place within the chassis during removal of the motherboard since it is not essential in such a circumstance to protect the motherboard from foreign bodies. Thus, according to yet another aspect, the invention provides a frame for an electronics assembly, which comprises:
(i) a first location for receiving a planar motherboard;
(ii) a second location for receiving at least one daughterboard so that it extends in a direction substantially perpendicular to the motherboard; and
(iii) a protective shield for the motherboard that extends in a plane substantially parallel to the plane of the motherboard and is located between the first location for receiving the motherboard and the second location for receiving the or each daughterboard.
In this case, the protective shield could be a plate-like structure that is arranged above the location in the frame for receiving the motherboard. The protective shield could, however, form part of a protective housing that surrounds the motherboard, provided that the motherboard can be removed therefrom when it is to be removed from the frame as a whole. Thus, for example, the protective housing could have a removable proximal surface which, when removed, will expose an opening for removal of the motherboard.
Where the protective shield is removable from the frame of the assembly together with the motherboard, the combination thereof with the motherboard is itself novel and so according to yet a further aspect, the invention provides a circuit board assembly for an electronics system, which comprises a planar printed circuit board having at least one electrical connector on a major surface thereof to allow the printed circuit board to be connected to one or more other printed circuit boards extending in a plane generally perpendicular to the plane thereof, and a protective shield that extends over the major surface, the shield having one or more apertures therein in register with the or each electrical connector.